In recent years, such wheelchairs have been developed as self-running type of wheelchairs provided with an electric motor operated by a rider using a joystick, and electric motor-assisted type of wheelchairs in which the rider's physical force applied to the handle rims is detected and assisted with an electric driving motor.
Nursing type of wheelchairs have also been conventionally used in which handle grips are attached to the top of right and left back pipes. A type of wheelchair has also been proposed in which an electric motor is mounted on the nursing type of wheelchair, and the value of nursing person's human force applied to the handle grips is detected to assist the human force according to the detected value (JP-A-6-304207).
In the wheelchair of the electric motor-assisted type, the rotation speed of the electric motor is appropriately reduced before being transmitted to the rear wheel. As a mechanism for reducing the rotation speed, for example a planetary gear mechanism is used.
In case the planetary gear mechanism is provided, the wheelchair, when its electric motor is deactivated, cannot be moved lightly by hand because the drive motor, the speed reduction mechanism, etc. work as a resistance. In order to improve the ease of manual handling in the above case, it is a general practice to provide a some type of clutch between the planetary gear mechanism and the rear wheel.
However, providing such a clutch complicates the constitution, and causes the problems of increased size and cost of the drive unit.
In particular from now on, the time is expected to come when aged people take care of aged people, and the wheelchair to be used there will be required of excellent functions for the nursing side. Namely, a wheelchair that is light-weight, compact, easy to handle, and low in price will be in demand.
This invention made in view of the above conventional situation aims at providing a drive unit for electric motor-operated vehicles that is light-weight, compact, and in particular makes it easy to handle the vehicle when its power supply is turned off.